Background and Objectives: This study aims to determine the relationship between pain, muscle strength, function, and quality of life (QoL) in overhead players with chronic shoulder internal impingement syndrome. Methods: Forty-seven overhead players consisting of 15 men, 32 and women (mean age 32.45±7.2) with chronic shoulder internal impingement were enrolled. The pain was measured by a visual analogue scale (VAS). Disabilities of the arm, shoulder, and hand (DASH) and shoulder pain and disability index (SPADI) questionnaires were used to measure pain and function, and a short form (SF)-36 questionnaire to measure QoL. Muscle strengths were evaluated in both hands with a hand-held dynamometer and players were asked to hold the maximal voluntary isometric contraction (MVIC) in the middle range for 3 s and rest for 30 s between each test and each contraction was repeated three times on both affected and healthy side and the average of contractions was considered for each side. Results: The study showed a significant relationship between pain, the strength of shoulder muscle groups (-0.354), function (-0.935), and QoL (-0.861) in overhead throwers with chronic shoulder internal impingement syndrome and the strength of internal rotators of the affected shoulder decreased more than others. (P<0.05) Conclusions: This correlational study showed a significant relationship between pain and strength of shoulder muscles and function and QoL in overhead throwers with this syndrome.